Former Senate Majority Leader Dean Skelos’ conviction on eight public corruption charges means that Gov. Cuomo “can’t hide this time’’ when it comes to getting a Democratic elected to the Senate, a senior state Dem has told The Post.

Cuomo has worked behind the scenes for years helping Republicans gain or keep their narrow control of the Senate in order to restrain the “progressive’’ tax-and-spend wing of his own Democratic Party — most recently earlier this fall, when he picked and then failed to support Barbara Fiala, who suffered a humiliating defeat in a special Binghamton-area Senate election.

But Skelos’ Nassau County district has more Democrats then Republicans, unlike the Binghamton district, and his high-profile conviction, combined with ongoing investigations of possible corruption by other Nassau Republican officials, has created the climate for a major Democratic win, insiders from both parties agree.

“Skelos’ seat is majority Democrat, it’s in the New York City media market, and the Democrats will have an unbeatable candidate, no thanks to Cuomo,’’ the senior Democrat told The Post.

“Unlike Binghamton, all eyes will be on this Senate race, and Cuomo must go all out to help win it or be permanently damaged. He can’t hide this time,’’ the Democrat said.

A second prominent Democrat said, “Can you imagine what Mayor de Blasio will say about Cuomo if the governor fails to back the Democratic candidate?” a reference to the ongoing feud between the governor and the mayor.

Democrats are expected to endorse Assemblyman Todd Kaminsky — a former federal prosecutor who has a stellar anti-corruption résumé, including the successful prosecution of former Senate Majority Leader Pedro Espada Jr. (D-Bronx) — for the Skelos seat, while Nassau Republicans, who suffered a surprise upset defeat in the race for district attorney last month, are having trouble recruiting a candidate.

Republicans also face the likelihood that the Skelos-seat battle will be a multimillion-dollar drain on their campaign war chest that will, should the Democrat win, leave them with reduced prospects of raising large sums for the November elections.

“The Republicans are going to have to spend millions defending Skelos’ seat with no guarantee of success,’’ said former state GOP Executive Director Brendan Quinn.

“Skelos’ legacy will not be only to be disgraced, and disbarred, and ejected from the Senate, it may well finally be the end of the GOP majority in the Senate.’’